Method for fabricating an optical waveguide

ABSTRACT

A method in which a separate preformed optical material is suitably sized for easy handling, manipulation, and fabrication into a waveguide having a core (formed from the optical material) having transverse cross-sectional dimensions on the order of only tens of microns. The method may include a plurality of mechanical steps, e.g., lapping, polishing, and/or dicing, and bonding steps, e.g., attaching with adhesives. In one embodiment, the method includes the steps of providing an optical material, thinning and polishing the optical material to form a core comprising a plurality of longitudinally extending surfaces, providing a plurality of support substrates, and attaching the plurality of support substrates to the longitudinally extending surfaces of the core. The plurality of support substrates may be attached to the plurality of longitudinally extending surfaces of the optical material with an adhesive. The optical material may include a high refractive index, and the plurality of support substrates and/or the adhesive may include a low refractive index.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/121,455 filed Jul. 23, 1998 and entitled “METHOD FOR FABRICATINGOPTICAL WAVEGUIDE”, now U.S. Pat. No. 6,270,604, and also relates to thefollowing commonly assigned patent application.

U.S. patent application Ser. No. 09/121,454, and entitled “OpticalWaveguide with Dissimilar Core and Cladding Materials, and LightEmitting Device Employing Same.”

This application is hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

This invention relates in general to waveguides, and in particular tonovel methods for fabricating optical waveguides.

BACKGROUND INFORMATION

Waveguides constrain or guide the propagation of electromagnetic wavesalong a path defined by the physical construction of the waveguide. Theuse of optical channel waveguides is widespread in integrated opticalcircuits. In particular, an optical channel waveguide provides bothvertical and lateral confinement of an optical wave while allowinglow-loss signal propagation.

An optical channel waveguide having small cross-sectional dimensionsallows high optical power densities to be established for moderateoptical input powers while the waveguiding nature provides potentiallylong interaction lengths. This combination of effects is extremelyattractive for a variety of optical functions such as second harmonicgeneration, optical amplification, wavelength conversion, and phasemodulation (when an appropriate electrode geometry is incorporated).

In general, a goal of waveguide fabrication is to produce waveguideswhich support a single guided mode of propagation of the electromagneticwaves. A number of techniques have been used with considerable successto fabricate optical channel waveguides. These include ion-exchange inglass substrates, ion indiffusion or proton exchange in LiNbO₃substrates, pattern definition by laser ablation, photolithography ofspun polymer films, and epitaxial growth and selective etching ofcompound semiconductor films.

A drawback of these techniques is that they cannot be used with asignificant number of useful optical materials, e.g., many lasercrystals. Another drawback of these prior art techniques is that theequipment required to fabricate the optical waveguide is expensive.

Therefore, there is a need for methods for forming optical waveguidesfrom separate preformed optical materials in which the methods comprisea plurality of mechanical processing steps, e.g., lapping, polishing,and/or dicing, and bonding steps, e.g., attaching with adhesives. Suchmethods are adaptable to fabrication of optical waveguides from any, ifnot all, optical materials. Furthermore, such methods are suitablyperformed using readily available and inexpensive equipment.

SUMMARY OF THE INVENTION

Pursuant to the present invention, the shortcomings of the prior art areovercome and additional advantages provided through the provision of amethod for forming an optical waveguide from separate preformedmaterials. For example, one embodiment of the method for forming anoptical waveguide comprises the steps of providing an assemblycomprising an optical material between a first support substrate and asecond support substrate, providing a third support substrate and afourth support substrate, and attaching to opposite surfaces of theassembly, a third support substrate and a fourth support substrate,wherein the opposite surfaces each comprise the first support substrate,the optical material, and the second support substrate.

In one expect of the invention, the step of providing the assemblycomprises providing the optical material comprising a polished surface,attaching the polished surface to the first substrate, thinning andpolishing a second surface of the optical material, and attaching asecond support substrate to the second polished surface.

In another aspect of the invention, the step of attaching oppositesurfaces of the assembly between a third support substrate and a fourthsupport substrate comprises the steps of polishing a surface of theassembly, wherein the surface comprises the first support substrate, theoptical material, and the second support substrate, attaching thepolished surface of the assembly to the third support substrate,thinning and polishing an opposite surface of the assembly, wherein theopposite surface comprises the first support substrate, the opticalmaterial, and the second support substrate, and attaching the oppositepolished surface to the fourth support substrate.

In another aspect of the present invention, the method furthercomprising the step of dicing the first assembly to form a plurality ofassemblies, wherein each of the plurality of assemblies is attachable toseparate support structures for forming separate optical waveguides.

In another embodiment of the present invention for forming a waveguide,the method comprising the steps of providing an optical material,thinning and polishing the optical material to form a core comprising aplurality of longitudinally extending surfaces, providing a plurality ofsupport substrates, and adhesively attaching the plurality of supportsubstrates to the longitudinally extending surfaces of the core.Desirably, the plurality of support substrates are attached to theplurality of longitudinally extending surfaces of the optical materialwith an adhesive. The optical material may comprise a high refractiveindex, and the plurality of support substrates and/or the adhesive maycomprise a low refractive index.

The optical waveguides fabricated according to the present invention,when the core comprises an optical gain material, are particularlysuitable for lasers and amplified spontaneous emission (ASE) sources forimaging and spectroscopy applications where multi-mode fibers are usedto handle high power, as well as test instrumentation for thetelecommunications and cable television industries where single modedelivery is required. Additional and detailed uses of the opticalwaveguides of the present invention are described in theabove-incorporated application.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-described objects, advantages and features of the presentinvention, as well as others, will be more readily understood from thefollowing detailed description of certain proffered embodiments of theinvention, when considered in connection with the accompanying drawingsin which:

FIG. 1 is a perspective view of an optical waveguide fabricated inaccordance with the methods of the present invention;

FIGS. 2A-2H are diagrammatic illustrations of one embodiment of thefabrication sequence for forming the optical waveguide shown in FIG. 1;and

FIGS. 3A and 3B together provide a flowchart of the fabrication sequenceof the optical waveguide shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, therein illustrated is one embodiment of anoptical waveguide 10 constructed in accordance with the principles ofthe present invention. As explained in greater detail below, a novelseries of successive precision polishing and bonding steps allows quickand inexpensive fabrication of waveguide 10 having a core 12 surroundedby suitable cladding or support substrate 14. For use as an opticalwaveguide, core 12 comprises a high refractive index while cladding orsupport substrate 14 comprises a low refractive index. For example,optical material 12 may comprise a relatively expensive laser crystal,and cladding or support substrate 14 may comprise a relatively low costglass material, e.g., fused silica.

In the illustrated embodiment shown in FIG. 1, optical waveguide 10 isin the form of a channel waveguide having a substantially squarecross-section. The elongated shape of core 12 provides a propagationaxis a, therein which may be longitudinally aligned with the outersurfaces of the support substrate.

The fabrication of optical waveguide 10 comprises a multi-step processof precision polishing and/or lapping techniques to mechanically thin apreformed optical material to form a core of the optical waveguidehaving a desired thickness in both the lateral and the verticalorientations. Optical adhesives are used to bond the core to preformedsurrounding support substrates. The core and the cladding or supportsubstrate may comprise dissimilar materials, e.g., materials which arestructurally and/or chemically distinct, and which have been separatelyfabricated as physically different materials and brought together duringthe assembly process for the optical waveguide.

Advantageously, the various methods according to the present inventionmay be performed by a machinist in which separate preformed opticalmaterials are initially suitably sized for easy manipulation andfabrication according to the present invention. For example, aninitially sized optical material may have a width of about 20 mm, alength of about 20 mm, and a thickness of about 0.5 mm to about 1 mm foreasy manipulation, and which may be fabricated into a core of an opticalwaveguide in which the core has cross-sectional dimensions on the orderof only tens of microns.

FIGS. 2A-2H diagrammatically illustrate a sequence of steps of oneembodiment according to the present invention for fabricating opticalwaveguide 10. FIGS. 3A and 3B together form a flowchart which describeseach of the steps illustrated in FIGS. 2A-2H in greater detail.

In this illustrated and described method, core 12 (best illustrated inFIGS. 1 and 2H) of optical waveguide 10 desirably has a squarecross-section that measures, e.g., 20 μm×20 μm. Thus, the separatepreformed materials used in the fabrication of optical waveguide 10 havebeen shown out of scale in the drawings for purposes of illustration.

In this illustrated method, initially an optical material 20 (from whichcore 12 will be formed) is attached to a first support substrate 30. Forexample, optical material 20 may be planar in shape having a width ofabout 20 mm, a length of about 20 mm, and a thickness of about 0.5 mm toabout 1 mm. First support substrate 30 may also be planar in shapehaving a width of about 20 mm, a length of about 20 mm, and a thicknessof about 2 mm.

Optical material 20 comprises a bottom surface 22 and a top surface 24.Prior to attaching optical material 20 to first support substrate 30,bottom surface 22 may be optically polished flat and smooth, e.g., sothat the surface becomes transparent. Bottom surface 22 may be opticallypolished by standard lapping and polishing techniques, e.g., in whichthe optical material is moved over a flat plate on which a liquidabrasive has been poured. The process of lapping and polishing may usewater-based slurries with varying particle sizes (e.g., about 0.5 μm toabout 9 μm) and types of abrasives (e.g., aluminum oxide and ceriumoxide). The dimensions of the optical material can be measured using amicrometer gauge with processing being terminated upon reaching thedesired surface quality and/or thickness. Accuracies of about 1 μm canbe achieved. In addition, the use of high precision polishing jigsallows exceptional flatness of surfaces, as well as, surfaces beingparallel (and/or perpendicular) to each other.

A value of flatness suitable for surface 22 may be determined based onthe wavelength of light for which the optical waveguide will be used.For example, where the optical waveguide will be used with light havinga wavelength of 1 μm, a suitable flatness may be about 0.05 μm over,e.g., the length or the thickness. In addition, surface 22 desirably hasa smooth surface quality, i.e., little, if any scratches, pits orsurface damage. For example, surface 22 desirably has a scratch to digdesignation of about 5-10 which is typically desired in opticalcomponents for use in laser applications.

A top surface 32 of first support substrate 30 may be opticallypolished, e.g., by lapping and polishing, as described above withreference to surface 22 of optical material 20, so that the surface isflat and smooth. Optically polished surfaces 22 and 32 may then beadhesively attached to each other with a suitable layer of opticaladhesive 40. Desirably, layer of optical adhesive 40 is formed with athickness less than about 2 μm.

With reference to FIG. 2B, in which optical material 20 is attached tofirst support substrate 30, top surface 24 (FIG. 2A) is thinned andoptically polished, e.g., by lapping to reduce the thickness a carefullycontrolled amount and polishing to obtain an optically polished surface26 as described above. In this illustrated method of fabrication,optical material 20 initially comprises a thickness of about 0.5 toabout 1 mm, which is reduced in thickness to about 20 μm.

A second support substrate 50 is then attached to optically polishedsurface 26 of the thinned optical material 20 to form an assembly 70, asshown in FIG. 2C. A bottom surface 52 of second support substrate 50 maybe optically polished, e.g., by lapping and polishing as describedabove, so that the surface is flat and smooth. Optically polishedsurfaces 52 and 26 may then be adhesively attached to each other with asuitable layer of optical adhesive 60. Desirably, second supportsubstrate 50 may be planar in shape having a width of about 20 mm, alength of about 20 mm, and a thickness of about 2 mm. Layer of opticaladhesive 60 desirably has a thickness less than about 2 μm.

As shown in FIG. 2D, assembly 70 (FIG. 2C) may be cut or diced throughsecond support substrate 50, thinned optical material 20, and firstsupport substrate 30, into a plurality of about 0.5 mm to about 1 mmthick slices 80. For example, assembly 70 may be diced using a diamondblade saw, wire saw, or wafer dicing machine.

Each slice 80 may be processed into a separate waveguide according tothe following method steps in which slice 80 is laid flat and sandwichedbetween two separate support substrates. Advantageously, simultaneousprocessing of slices 80 results in the production of multiple opticalwaveguides allowing the process to be cost effective.

With reference to a single slice 80, as shown in FIG. 2E, a surface 82of slice 80 in which surface 82 comprises first support substrate 30,optical material 20, and second support substrate 50, is opticallypolished, e.g., by lapping and polishing as described above, so that thesurface is flat and smooth.

Surface 82 of slice 80 is then attached to a third support substrate 90as shown in FIG. 2F. A top surface 92 of third support substrate 90 maybe optically polished, e.g., by lapping and polishing as describedabove, so that the surface is flat and smooth. Optically polishedsurfaces 92 and 82 may then be adhesively attached to each other with asuitable layer of optical adhesive 100. In this exemplary embodiment,third support substrate 90 may be planar in shape having a width ofabout 4 mm, a length of about 20 mm, and a thickness of about 2 mm.Layer of optical adhesive 100 desirably has a thickness less than about2 μm.

With reference to FIG. 2G, after slice 80 is attached to third supportsubstrate 90, a surface 84 (FIG. 2F) is thinned and optically polished,e.g., by lapping and polishing as described above, to reduce thethickness a carefully controlled amount and to obtain a flat polishedsurface 86. In this illustrated method of fabrication, slice 80initially comprises a thickness of about 0.5 to about 1 mm and isreduced in thickness to about 20 μm, so that core 12 is formed having asubstantially square transverse cross-section that measures 20 μm×20 μm.

As shown in FIG. 2H, a fourth support substrate 110 is attached tooptically polished surface 86 of slice 80 to form optical waveguide 10.A surface 112 of fourth support substrate 110 may be optically polished,e.g., by lapping and polishing as described above, so that the surfaceis flat and smooth. Optically polished surfaces 112 and 86 may then beadhesively attached to each other with a suitable layer of opticaladhesive 120. In this exemplary embodiment, fourth support substrate 100may be planar in shape having a width of about 4 mm, a length of about20 mm, and a thickness of about 2 mm. Layer of optical adhesive 120desirably has a thickness of less than about 2 μm. Preferably, first end16 and second end 18 of optical waveguide 10 are optically polished.Wavelength-dependent optically reflective materials may be applied overthe optical waveguide ends 16 and 18 to form an optical cavity whichallows introduction of a pump energy at a predetermined wavelength intothe optical waveguide and also allow radiation emission from the opticalwaveguide at a desired source wavelength.

Desirably, the mating surfaces of the optical material and thesubstrates have the same surface quality, and the thickness of the layerof adhesive between each of the mating surfaces is the same.

While the illustrated and disclosed method of fabricating a waveguide inwhich a thin, e.g., less than about 2 μm thick layer of optical adhesiveis used to attach the substrates to the optical material, from thepresent description it will be appreciated by those skilled in the artthat a layer of optical adhesive having a greater thickness may be used.For example, with a greater thickness layer of optical adhesive, e.g.,greater than about 3 μm, the adhesive layer itself may provide suitablecladding to influence the waveguide properties. In this alternativeembodiment, it would not be necessary to optically polish surfaces ofthe support substrate which mate with surfaces of optical material 20and/or core 12. In this situation, the support substrates can beselected for their processing qualities irrespective of the refractiveindex. It should be noted that, for maintaining the surfaces of opticaladhesive cladding layer, parallel and perpendicular to the core, and formaintaining the layer of optical adhesive at a constant thickness, itmay be desirable to optically polish surfaces of the support substrates.In addition, practical issues such as edge breakage and differentialpolishing rates between the adhesive and core/cladding materials need tobe considered in selecting appropriate optical adhesives and layerthickness.

Suitable optical waveguide assemblies fabricated from the methodsaccording to the present invention may have dimensions in the range ofabout 2-5 mm×about 2-5 mm in cross-section and 5-30 mm in lengthalthough greater lengths are possible. This allows easy handling andmechanical fixturing of the optical waveguide during manufacture andoptical testing.

Support structures 30, 50, 90, and 110 preferably comprise the samematerial having the same refractive index, e.g., being initially cutfrom a single common substrate. Layers of optical adhesive 40, 60, 100and 120, desirably comprise the same optical adhesive having arefractive index desirably corresponding to the refractive index of thesupport substrates. Also desirably, the layers of optical adhesiveprovide adequate edge support to optical material 20 and supportsubstrates 30, 50, 90, and 110 during the polishing and/or dicing stepsso that degradation of the edges of the optical material and/or supportsubstrates is minimized. Optical adhesives for use in the methodaccording to the present invention may be suitable ultraviolet curedoptical adhesives, e.g., Norland 61 manufactured and available fromNorland Products Inc., of New Brunswick, N.J.

In order to improve the optical properties of optical waveguide 10(e.g., polarization dependence), preferably optically polished surface26 is substantially parallel to optically polished surface 22, opticallypolished surface 82 is substantially parallel to optically polishedsurface 86, and each of the four adjacent surfaces, e.g., opticallypolished surface 26 and 82, are substantially perpendicular to eachother.

The fabrication process according to the present invention is alsocompatible with most optical materials, e.g., active materials such aslaser crystals or doped glass for use as lasers, amplifiers, ASE sourcesand wavelength converters. Suitable active materials include LiNbO₃,Nd:YAG, Nd:Glass, Nd:YLF, Nd:LiNbO₃, Er:YAG, Er:Glass, Er:LiNbO₃,Er:Silicon, Cr:Forsterite, Cr:YAG, and Ti:Al₂O₃.

Table I presents various waveguide examples for a 1300 nm ASE source inaccordance with the present invention. Note that these combinations areprovided by way of example only, and there are countless additionalwaveguide formations which are possible. In each formation, however, thecore material and cladding material will comprise structurally and/orchemically distinct materials which have been separately fabricated fromphysically different materials that are then brought together during theassembly process of the optical waveguide.

TABLE I Cladding material Core material Fused silica (n = 1.45) Nd-dopedYAG (n = 1.81) Soda-lime glass (n = 1.5) Nd-doped YAG (n = 1.81) Fusedsilica (n = 1.45) Nd-doped phosphate glass (n = 1.56) Fused silica (n =1.45) Cr-doped Forsterite (n = 1.56) Fused silica (n = 1.45) SFL6 dopedglass (n = 1.76) Magnesium fluoride (n = 1.38) Lithium niobate (n = 2.2)Fused silica (n = 1.45) Lithium niobate (n = 2.2) Soda-lime glass (n =1.5) Cr-doped YAG (n = 1.8)

While the illustrated optical waveguide is shown as an optical channelwaveguide having a square cross-section, e.g., 20 μm by 20 μm core, fromthe present description it will be appreciated by those skilled in theart that optical waveguides may be fabricated by the methods of thepresent invention to have other cross-sectional configurations dependingon the particular application and the desired propagation of an opticalsignal within the waveguide. For example, optical waveguides fabricatedaccording to the present invention may be in the form of planar or slaboptical waveguides having a rectangular transverse cross-section.

While the invention has been particularly shown and described withreference to preferred embodiment(s) thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A method for forming an optical waveguide, saidmethod comprising: attaching with an adhesive a first surface of anoptical material to a first support substrate, and a second surface ofsaid optical material to a second support substrate to form anadhesively attached assembly; and attaching with an adhesive oppositesurfaces of at least a portion of said adhesively attached assembly to athird support substrate and to a fourth support substrate, said oppositesurfaces each comprising at least portions of said first supportsubstrate, said optical material, and said second support substrate. 2.The method of claim 1 wherein said optical material comprises a firstmaterial, said support substrates comprise a second material, andwherein said first material is at least one of structurally andchemically dissimilar from said second material.
 3. The method of claim2 wherein said optical material comprises a crystalline material andsaid support substrates comprise an amorphous material.
 4. The method ofclaim 2 wherein said optical material comprises phosphate glass.
 5. Themethod of claim 4 wherein said optical material comprises erbium dopedglass.
 6. The method of claim 4 wherein said support substrates comprisefused silica.
 7. The method of claim 2 wherein said optical materialcomprises an active material.
 8. The method of claim 1 furthercomprising polishing uncovered opposite ends of said optical materialand applying a reflective material thereto.
 9. The method of claim 1further comprising thinning said optical material prior to polishingsaid second surface.
 10. The method of claim 1 wherein said attachingsaid opposite surfaces to said third support substrate and to saidfourth support substrate comprises attaching said third supportsubstrate to one of said opposite surfaces of said adhesively attachedassembly, thinning said adhesively attached assembly after adhesivelyattaching said third support substrate to said adhesively attachedassembly, and attaching said forth support substrate to the other ofsaid opposite surfaces of said adhesively attached assembly.
 11. Themethod of claim 1 wherein said providing said third and fourth supportsubstrates comprises providing said third support substrate comprising apolished surface and providing said fourth support substrate comprisinga polished surface.
 12. The method of claim 1 further comprising dicingsaid adhesively attached assembly to form a plurality of adhesivelyattached assemblies, wherein each of said plurality of adhesivelyattached assemblies is attachable to separate support substrates forforming separate optical waveguides.
 13. A method for forming an opticalwaveguide, said method comprising: providing an assembly comprising anoptical material disposed between and adhesively attached to a firstsupport substrate and to a second support substrate; and attaching withan adhesive opposite surfaces of at least a portion of said adhesivelyattached assembly to a third support substrate and to a fourth supportsubstrate, said opposite surfaces each comprising at least portions ofsaid first support substrate, said optical material, and said secondsupport substrate.
 14. The method of claim 13 wherein said opticalmaterial comprises a first material, said support substrates comprise asecond material, and wherein said first material is at least one ofstructurally and chemically dissimilar from said second material. 15.The method of claim 14 wherein said optical material comprises acrystalline material and said support substrates comprise an amorphousmaterial.
 16. The method of claim 14 wherein said optical materialcomprises phosphate glass.
 17. The method of claim 16 wherein saidoptical material comprises erbium doped glass.
 18. The method of claim16 wherein said support substrates comprise fused silica.
 19. The methodof claim 17 wherein said optical material comprises an active material.20. The method of claim 13 further comprising polishing uncoveredopposite ends of said optical material and applying a reflectivematerial thereto.
 21. The method of claim 13 further comprising thinningsaid assembly prior to polishing said opposite surface.
 22. The methodof claim 13 wherein said providing said third and fourth supportsubstrates comprise providing said third support substrate comprising apolished surface and providing said fourth support substrate comprisinga polished surface.
 23. The method of claim 13 further comprising dicingsaid adhesively attached assembly to form a plurality of adhesivelyattached assemblies, wherein each of said plurality of adhesivelyattached assemblies is attachable to separate support substrates forforming separate optical waveguides.
 24. A method for forming aplurality of waveguides, said method comprising: dicing an adhesivelyattached assembly comprising an optical material disposed between andadhesively attached to a first support substrate and to a second supportsubstrate to provide a plurality of adhesively attached assemblies eachof which comprising a portion of said optical material disposed betweenand adhesively attached to a portion of said first support substrate andto a portion of a second support substrate; providing a plurality ofthird support substrates; attaching with an adhesive a first surface ofat least portions of said first support substrate, said opticalmaterial, and said second support substrate of said adhesively attachedassemblies to said plurality of third support substrates; providing aplurality of fourth support substrates; and attaching with said adhesivea second surface of at least portions of said first support substrate,said optical material, and said second support substrate of saidadhesively attached assemblies to said plurality of fourth supportsubstrates.
 25. The method of claim 24 wherein said optical materialcomprises a first material, said support substrates comprise a secondmaterial, and wherein said first material is at least one ofstructurally and chemically dissimilar from said second material. 26.The method of claim 25 wherein said optical material comprises acrystalline material and said support substrates comprise an amorphousmaterial.
 27. The method of claim 25 wherein said optical materialcomprises phosphate glass.
 28. The method of claim 27 wherein saidoptical material comprises erbium doped glass.
 29. The method of claim27 wherein said support substrates comprise fused silica.
 30. The methodof claim 24 wherein said optical material comprises an active material.31. The method of claim 24 further comprising polishing uncoveredopposite ends of said optical material and applying a reflectivematerial thereto.
 32. The method of claim 24 further comprising thinningsaid optical material prior to polishing said second surface.
 33. Themethod of claim 32 further comprising thinning said assembly prior topolishing said opposite surface.
 34. A method for forming an opticalwaveguide, said method comprising: providing an optical material;providing a first support substrate, a second support substrate, a thirdsupport substrate, and a fourth support substrate, said optical materialcomprising a first material and said support substrates comprising asecond material, said first material being at least one of structurallyand chemically dissimilar from said second material; attaching with anadhesive a first surface of said optical material to said first supportsubstrate, and a second surface of said optical material to said secondsupport substrate to form an adhesively attached assembly; and attachingwith an adhesive opposite surfaces of at least a portion of saidadhesively attached assembly to said third support substrate and to saidfourth support substrate, said opposite surfaces each comprising atleast portions of said first support substrate, said optical material,and said second support substrate.
 35. The method of claim 34 whereinsaid optical material comprises a crystalline material and said supportsubstrates comprise an amorphous material.
 36. The method of claim 34wherein said optical material comprises phosphate glass.
 37. The methodof claim 36 wherein said optical material comprises erbium doped glass.38. The method of claim 36 wherein said support substrates comprisefused silica.
 39. The method of claim 36 further comprising polishinguncovered opposite ends of said optical material and applying areflective material thereto.
 40. The method of claim 36 furthercomprising thinning said optical material prior to polishing said secondsurface.
 41. The method of claim 40 further comprising thinning saidadhesively attached assembly prior to polishing said opposite surface.42. The method of claim 34 further comprising dicing said adhesivelyattached assembly to form a plurality of assemblies, wherein each ofsaid plurality of assemblies is attachable to separate supportsubstrates for forming separate optical waveguides.
 43. A method forforming an optical waveguide, said method comprising: attaching with anadhesive four surfaces of an optical material to respective separatesupport substrates.
 44. The method of claim 43 wherein said opticalmaterial comprises a first material, said support substrates comprise asecond material, and wherein said first material is at least one ofstructurally and chemically dissimilar from said second material. 45.The method of claim 43 further comprising providing said opticalmaterial and thinning said optical material to form said surfaces. 46.The method of claim 43 further comprising polishing at least one of saidsurfaces after adhesively attaching at least one of said supportsubstrates to at least one different surface of said surfaces.
 47. Themethod of claim 43 wherein said optical material comprises a crystallinematerial and said support substrates comprise an amorphous material. 48.The method of claim 43 wherein said optical material comprises phosphateglass.
 49. The method of claim 48 wherein said optical materialcomprises erbium doped glass.
 50. The method of claim 48 wherein saidsupport substrates comprise fused silica.
 51. The method of claim 43wherein said optical material comprise an active material.
 52. Themethod of claim 43 further comprising polishing uncovered opposite endsof said optical material and applying a reflective material thereto. 53.A method for forming an adhesively attached assembly for use in formingan optical waveguide, said method comprising: providing an opticalmaterial; providing a first support substrate; providing an adhesive;attaching with said adhesive said optical material to said first supportsubstrate; providing a second support substrate; and attaching with saidadhesive said optical material to said second support substrate to formthe adhesively attached assembly.
 54. The method of claim 53 whereinsaid optical material comprises a first material, said supportsubstrates comprise a second material, and wherein said first materialis at least one of structurally and chemically dissimilar from saidsecond material.
 55. The method of claim 54 wherein said opticalmaterial comprises a crystalline material and said support substratescomprise an amorphous material.
 56. The method of claim 53 wherein saidoptical material comprises phosphate glass.
 57. The method of claim 56wherein said optical material comprises erbium doped glass.
 58. Themethod of claim 56 wherein said support substrates comprise fusedsilica.
 59. The method of claim 53 wherein said optical materialcomprises an active material.
 60. The method of claim 53 furthercomprising polishing opposite surfaces of said adhesively attachedassembly, said opposite polished surfaces comprising at least portionsof said first support substrate, said optical material, and said secondsupport substrate.
 61. The method of claim 53 further comprising dicingsaid assembly to form a plurality of assemblies, wherein each of saidplurality of assemblies is attachable to separate third and fourthsupport substrates for forming separate optical waveguides.
 62. Anoptical waveguide comprising: an elongated optical material having foursurfaces; and a plurality of support substrates each of which isadhesively attached to a different one of said four surfaces.
 63. Theoptical waveguide of claim 62 wherein said optical material comprises afirst material, said support substrates comprise a second material, andwherein said first material is at least one of structurally andchemically dissimilar from said second material.
 64. The opticalwaveguide of claim 63 wherein said optical material comprises acrystalline material and said support substrates comprise an amorphousmaterial.
 65. The optical waveguide of claim 63 wherein said opticalmaterial comprises phosphate glass.
 66. The optical waveguide of claim65 wherein said optical material comprises erbium doped glass.
 67. Theoptical waveguide of claim 65 wherein said support substrates comprisedfused silica.
 68. The optical waveguide of claim 62 wherein said opticalmaterial comprises an active material.
 69. The optical waveguide ofclaim 62 wherein said optical material comprises polished opposite endsand a reflective material disposed thereon.
 70. An assembly for use informing a plurality of optical waveguides, said assembly comprising: anoptical material having first and second surfaces; a first supportsubstrate adhesively attached to said first surface; a second supportsubstrate adhesively attached to said second surface; and wherein saidoptical material comprises a first material, said support substratescomprise a second material, and said first material is at least one ofstructurally and chemically dissimilar from said second material. 71.The assembly of claim 70 wherein said optical material comprises acrystalline material and said support substrates comprise an amorphousmaterial.
 72. The assembly of claim 70 wherein said optical materialcomprises phosphate glass.
 73. The assembly of claim 72 wherein saidoptical material comprises erbium doped glass.
 74. The assembly of claim72 wherein said support substrates comprise fused silica.
 75. Theassembly of claim 70 wherein said optical material comprises an activematerial.
 76. The assembly of claim 70 further comprising oppositepolished surfaces, said opposite polished surfaces comprising said firstsupport substrate, said optical material, and said second supportsubstrate.